9. Выполните вычитание: a) -3,6-4,7 в) 4$$\frac{1}{3}-5\frac{2}{7}$$ б) 6,3-(-8,1) г) -6$$\frac{5}{24}-(-5\frac{13}{30})$$

Выполним вычитание:

1. a) $$-3.6 - 4.7 = -8.3$$
2. б) $$6.3 - (-8.1) = 6.3 + 8.1 = 14.4$$
3. в) $$4\frac{1}{3} - 5\frac{2}{7} = \frac{4 \cdot 3 + 1}{3} - \frac{5 \cdot 7 + 2}{7} = \frac{13}{3} - \frac{37}{7} = \frac{13 \cdot 7}{3 \cdot 7} - \frac{37 \cdot 3}{7 \cdot 3} = \frac{91}{21} - \frac{111}{21} = \frac{91-111}{21} = \frac{-20}{21} = -\frac{20}{21}$$
4. г) $$-6\frac{5}{24} - (-5\frac{13}{30}) = -6\frac{5}{24} + 5\frac{13}{30} = -6\frac{5 \cdot 5}{24 \cdot 5} + 5\frac{13 \cdot 4}{30 \cdot 4} = -6\frac{25}{120} + 5\frac{52}{120} = -6 + 5 + \frac{-25+52}{120} = -1 + \frac{27}{120} = -1 + \frac{9}{40} = -\frac{40}{40} + \frac{9}{40} = \frac{-40+9}{40} = \frac{-31}{40} = -\frac{31}{40}$$

Ответ:

1. a) -8.3
2. б) 14.4
3. в) $$\frac{-20}{21}$$
4. г) $$\frac{-31}{40}$$